(1) Field of the Invention
The present invention relates to a technique for cutting, along a circumferential edge of a semiconductor wafer, a protective tape joined to a surface of the semiconductor wafer with a pattern formed thereon for protecting the pattern.
(2) Description of the Related Art
In a conventional producing procedure of a semiconductor wafer, a back surface of a semiconductor wafer (hereinafter, simply referred to as “wafer”) is worked using a mechanical method such as a grinding method and a polishing method (CMP) or a chemical method such as an etching method, thereby reducing a thickness of the wafer. When the wafer is worked using such a method, a protective tape is joined to a surface for protecting a pattern formed on the surface.
That is, a surface (patterned surface) of a wafer transported to a back grind step is suction-held by a chuck table, and its back surface is ground by a grindstone. Herein, since stress caused by the grinding operation is applied to the surface of the wafer and there is a probability that the pattern is damaged or contaminated. Therefore, the protective tape is joined to the surface. After the protective tape is joined to the wafer, the protective tape is usually cut in the state where a tip end of a cutter blade is brought into contact with an outer circumference of the wafer (see JP-A 2003-209082 for example).
If the protective tape is cut in the state where the tip end of the cutter blade is brought into contact with the outer circumferential edge of the wafer, the tip end of the cutter blade is prone to be damaged by friction with respect to the wafer. In this state, if the protective tape joined to the surface of the wafer is cut, there is a problem that viscoelastic particle component of the protective tape protrudes from the cut portion and the particles are attached to the outer circumferential edge of the wafer. If the particles are attached to the protective tape, only this portion is ground and thinned by a subsequent back grinding operation, and variation of a thickness of a wafer is increased.